Golf Ball

ABSTRACT

The present invention is a golf ball having a core, a cover and a lattice structure aerodynamic pattern. The core has a diameter of 1.50 inches to 1.56 inches, and a PGA compression of 55 to 70 points. The cover has a thickness of 0.60 inch to 0.90 inch. The cover has a Shore D hardness less than 64 on the golf ball. The golf ball has a ball velocity off a driver at a medium speed that is greater than 132.7 mph.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] The Present Application is a continuation-in-part application ofco-pending U.S. patent application Ser. No. 09/768,846, filed on Jan.23, 2001.

FEDERAL RESEARCH STATEMENT

[0002] [Not Applicable ]

BACKGROUND OF INVENTION

[0003] 1. Field of the Invention

[0004] The present invention relates to a golf ball. More specifically,the present invention relates to a two-piece golf ball with a coverlayer composed of an ionomer blend, a core containing polybutadiene,tungsten, and other materials, and a tubular lattice structureaerodynamic pattern.

[0005] 2. Description of the Related Art

[0006] Two-piece golf balls with ionomer covers have been in existencesince the 1960's. The core is typically solid, and the cover is usuallya hard ionomer material. The two-piece golf balls of the prior artprovide added distance while giving up feel.

[0007] The traditional golf ball, as readily accepted by the consumingpublic, is spherical with a plurality of dimples, with each dimplehaving a circular cross-section. Many golf balls have been disclosedthat break with this tradition, however, for the most part thesenon-traditional golf balls have been commercially unsuccessful.

[0008] Most of these non-traditional golf balls still attempt to adhereto the Rules Of Golf as set forth by the United States Golf Association(USGA) and The Royal and Ancient Golf Club of Saint Andrews (R&A). Asset forth in Appendix III of the Rules of Golf, the weight of the ballshall not be greater than 1.620 ounces avoirdupois (45.93 gm), thediameter of the ball shall be not less than 1.680 inches (42.67 mm)which is satisfied if, under its own weight, a ball falls through a1.680 inches diameter ring gauge in fewer than 25 out of 100 randomlyselected positions, the test being carried out at a temperature of 23±1°C., and the ball must not be designed, manufactured or intentionallymodified to have properties which differ from those of a sphericallysymmetrical ball. Also, the Rules of Golf limit the initial velocity ofa golf ball to 250 feet (76.2 m) per second (a two percent maximumtolerance allows for an initial velocity of 255 per second) and theoverall distance to 280 yards (256 m) plus a six percent tolerance for atotal distance of 296.8 yards (the six percent tolerance may be loweredto four percent). A complete description of the Rules of Golf areavailable on the USGA web page at ww_Hlt509050176w_Hlt509050176.usga.orgor at the R&A web page at www.randa.org. Thus, the initial velocity andoverall distance of a golf ball must not exceed these limits in order toconform to the Rules of Golf.

[0009] One example is Shimosaka et al., U.S. Pat. No. 5,916,044, for aGolf Ball that discloses the use of protrusions to meet the 1.68 inch(42.67 mm) diameter limitation of the USGA and R&A. The Shimosaka patentdiscloses a golf ball with a plurality of dimples on the surface and afew rows of protrusions that have a height of 0.001 to 1.0 mm from thesurface. Thus, the diameter of the land area is less than 42.67 mm.

[0010] Another example of a non-traditional golf ball is Puckett et al.,U.S. Pat. No. 4,836,552 for a Short Distance Golf Ball, which disclosesa golf ball having brambles instead of dimples in order to reduce theflight distance to half of that of a traditional golf ball in order toplay on short distance courses.

[0011] Another example of a non-traditional golf ball is Pocklington,U.S. Pat. No. 5,536,013 for a Golf Ball, which discloses a golf ballhaving raised portions within each dimple, and also discloses dimples ofvarying geometric shapes such as squares, diamonds and pentagons. Theraised portions in each of the dimples of Pocklington assists incontrolling the overall volume of the dimples.

[0012] Another example is Kobayashi, U.S. Pat. No. 4,787,638 for a GolfBall, which discloses a golf ball having dimples with indentationswithin each of the dimples. The indentations in the dimples of Kobayashiare to reduce the air pressure drag at low speeds in order to increasethe distance.

[0013] Yet another example is Treadwell, U.S. Pat. No. 4,266,773 for aGolf Ball, which discloses a golf ball having rough bands and smoothbands on its surface in order to trip the boundary layer of air flowduring flight of the golf ball.

[0014] Aoyama, U.S. Pat. No. 4,830,378, for a Golf Ball With UniformLand Configuration, discloses a golf ball with dimples that havetriangular shapes. The total flat land area of Aoyama is no greater than20% of the surface of the golf ball, and the objective of the patent isto optimize the uniform land configuration and not the dimples.

[0015] Another variation in the shape of the dimples is set forth inSteifel, U.S. Pat. No. 5,890,975 for a Golf Ball And Method Of FormingDimples Thereon. Some of the dimples of Steifel are elongated to have anelliptical cross-section instead of a circular cross-section. Theelongated dimples make it possible to increase the surface coveragearea. A design patent to Steifel, U.S. Pat. No. 406,623, has allelongated dimples.

[0016] A variation on this theme is set forth in Moriyama et al., U.S.Pat. No. 5,722,903, for a Golf Ball, which discloses a golf ball withtraditional dimples and oval shaped dimples.

[0017] A further example of a non-traditional golf ball is set forth inShaw et al., U.S. Pat. No. 4,722,529, for Golf Balls, which discloses agolf ball with dimples and 30 bald patches in the shape of a dumbbellfor improvements in aerodynamics.

[0018] Another example of a non-traditional golf ball is Cadorniga, U.S.Pat. No. 5,470,076, for a Golf Ball, which discloses each of a pluralityof dimples having an additional recess. It is believed that the majorand minor recess dimples of Cadorniga create a smaller wake of airduring flight of a golf ball.

[0019] Oka et al., U.S. Pat. No. 5,143,377, for a Golf Ball, disclosescircular and non-circular dimples. The non-circular dimples are square,regular octagonal, regular hexagonal and amount to at least fortypercent of the 332 dimples on the golf ball of Oka. These non-circulardimples of Oka have a double slope that sweeps air away from theperiphery in order to make the air turbulent.

[0020] Machin, U.S. Pat. No. 5,377,989, for Golf Balls WithIsodiametrical Dimples, discloses a golf ball having dimples with an oddnumber of curved sides and arcuate apices to reduce the drag on the golfball during flight.

[0021] Lavallee et al., U.S. Pat. No. 5,356,150, discloses a golf ballhaving overlapping elongated dimples to obtain maximum dimple coverageon the surface of the golf ball.

[0022] Oka et al., U.S. Pat. No. 5,338,039, discloses a golf ball havingat least forty percent of its dimples with a polygonal shape. The shapesof the Oka golf ball are pentagonal, hexagonal and octagonal.

[0023] Although the prior art has set forth numerous variations for thesurface of a golf ball, there remains a need for a two-piece golf ballhaving a surface that minimizes the volume needed to trip the boundarylayer of air at low speed while providing a low drag level at highspeeds.

SUMMARY OF INVENTION

[0024] One aspect of the present invention is a golf ball having a core,a cover and a lattice structure aerodynamic pattern. The core has adiameter of 1.50 inches to 1.56 inches. The core is composed ofpolybutadiene, zinc oxide in an amount of 7 to 15 parts per hundredparts of polybutadiene, zinc diacryalate in an amount of 30 to 50 partsper hundred parts of polybutadiene, an initiator in an amount of 0.1 to1.0 parts per hundred parts of polybutadiene, and tungsten in an amountof 5 to 10 parts per hundred parts of polybutadiene. The core has a PGAcompression of 45 to 70 points. The cover preferably has a thickness of0.060 inch to 0.090 inch. The cover is preferably composed of an ionomerblend formed from a high acid copolymer ionomer neutralized with zincand a terpolymer ionomer neutralized with magnesium. The coverpreferably has a flexural modulus ranging from 35,000 psi to 60,000 psi,and a Shore D hardness ranging from 60 to 65. The golf ball has a PGAcompression ranging from 75 to 90 points.

[0025] Another aspect of the present invention is a golf ball that has aball velocity off a driver at a medium speed (about 79 miles per hour)that is greater than 132.7 mph, and a core, a cover and a latticestructure aerodynamic pattern. The core has a diameter of 1.50 inches to1.56 inches, and a PGA compression of 45 to 70 points. The cover has athickness of 0.060 inch to 0.090 inch. The cover has a Shore D hardnessless than 64 as measured on lattice structure.

[0026] Yet another aspect of the present invention is a golf ball thathas a ball velocity off a five iron at a medium speed that is greaterthan 115.0 mph, and a core, a cover and a lattice structure aerodynamicpattern. The core has a diameter of 1.50 inches to 1.56 inches, and aPGA compression of 45 to 70 points. The cover has a thickness of 0.060inch to 0.090 inch. The cover has a Shore D hardness less than 64 asmeasured on the lattice structure.

[0027] Yet another aspect of the present invention is a golf ball thathas a COR that is greater than 0.795 points, and a core, a cover and alattice structure aerodynamic pattern. The core has a diameter of 1.50inches to 1.56 inches, and a PGA compression of 55 to 70 points. Thecover has a thickness of 0.060 inch to 0.090 inch. The cover has a ShoreD hardness less than 64 as measured on the land surface of the golfball.

[0028] Having briefly described the present invention, the above andfurther objects, features and advantages thereof will be recognized bythose skilled in the pertinent art from the following detaileddescription of the invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

[0029]FIG. 1 is an equatorial view of a preferred embodiment of a golfball of the present invention.

[0030]FIG. 1A is a cross-sectional view of a golf ball of the presentinvention.

[0031]FIG. 2 is a polar view of the golf ball of FIG. 1.

[0032]FIG. 3 is an enlargement of a section of FIG. 1.

[0033]FIG. 4 is an enlargement of a section of FIG. 3 FIG. 4A is across-sectional view of the surface of the golf ball of the presentinvention illustrating an outersphere, also referred to as a phantomsphere.

[0034]FIG. 5 is a cross-sectional view of one embodiment of latticemembers of the golf ball of the present invention.

[0035]FIG. 6 is a cross-sectional view of an alternative embodiment oflattice members of the golf ball of the present invention.

[0036]FIG. 6A is a top plan view of FIG. 6 to illustrate the width ofthe apex of each of the lattice members.

[0037]FIG. 7 is an isolated cross-sectional view of one embodiment oflattice members of the golf ball of the present invention.

[0038]FIG. 8 is a cross-sectional view of a preferred embodiment oflattice members of the golf ball of the present invention.

[0039]FIG. 9 is a front view of the preferred embodiment of the golfball of the present invention illustrating the alternating parting line.

[0040]FIG. 9A is a perspective view of the golf ball of FIG. 9.

[0041]FIG. 9B is a polar view of the golf ball of FIG. 9.

[0042]FIG. 9C is an identical view of FIG. 9 illustrating the pentagonalgrouping of hexagons.

[0043]FIG. 10 is an enlarged view of the surface of a golf ball of thepresent invention to demonstrate the minimal volume feature of thepresent invention.

[0044]FIG. 11 is an enlarged view of the surface of a golf ball of theprior art for comparison to the minimal volume feature of the presentinvention.

[0045]FIG. 12 is a chart of the minimal volume.

[0046]FIG. 13 is a graph of the cover Shore D hardness (x-axis) versusthe Ball Velocity using a driver at a medium swing speed (y-axis) forthe golf ball of the present invention and 12 competitor golf balls.

[0047]FIG. 14 is a graph of the cover Shore D hardness (x-axis) versusthe Ball Velocity using a five-iron at a medium swing speed (y-axis) forthe golf ball of the present invention and 12 competitor golf balls.

DETAILED DESCRIPTION

[0048] As shown in FIGS. 1 and 1A, the golf ball of the presentinvention is generally designated 20. The golf ball 20 has a core 12 anda cover 14 encompassing the core. The surface of the golf ball 20 has alattice structure aerodynamic pattern.

[0049] The golf ball 20 has innersphere 21 with an innersphere surface22. The golf ball 20 also has an equator 24 dividing the golf ball 20into a first hemisphere 26 and a second hemisphere 28. A first pole 30is located ninety degrees along a longitudinal arc from the equator 24in the first hemisphere 26. A second pole 32 is located ninety degreesalong a longitudinal arc from the equator 24 in the second hemisphere28.

[0050] Descending toward the surface 22 of the innersphere 21 are aplurality of lattice members 40. In a preferred embodiment, the latticemembers 40 are tubular. However, those skilled in the pertinent art willrecognize that the lattice members 40 may have other similar shapes. Thelattice members 40 are connected to each other to form a latticestructure 42 on the golf ball 20. The interconnected lattice members 40form a plurality of polygons encompassing discrete areas of the surface22 of the innersphere 21. Most of these discrete bounded areas 44 arehexagonal shaped bounded areas 44 a, with a few pentagonal shapedbounded areas 44 b, a few octagonal shaped bounded areas 44 c, and a fewquadragonal shaped bounded areas 44 d. In the embodiment of FIGS. 1-4,there are 380 polygons. In an alternative embodiment, there are 332polygons.

[0051] In the preferred embodiment, each of the plurality of latticemembers 40 are connected to at least another lattice members 40. Each ofthe lattice members 40 meet at least two other lattice members 40 at avertex 46. Most of the vertices 46 are the congruence of three latticemembers 40. However, some vertices 46 a are the congruence of fourlattice members 40. These vertices 46 a are located at the equator 24 ofthe golf ball 20. The length of each of the lattice members 40 rangesfrom 0.005 inch to 0.01 inch thereby defining an outersphere of at least1.68 inches.

[0052] The preferred embodiment of the present invention has reduced theland to almost zero since only a line of each of the plurality oflattice members 40 is in a spherical plane at 1.68 inches, theoutersphere. More specifically, the land area of traditional golf ballsis the area forming a sphere of at least 1.68 inches for USGA and R&Aconforming golf balls. This land area is traditionally minimized withdimples that are concave into the surface of the sphere of thetraditional golf ball, resulting in land area on the non-dimpled surfaceof the golf ball. However, the golf ball 20 of the present invention hasonly a line at an apex 50 of each of the lattice members 40 that definesthe land area of the outersphere of the golf ball 20.

[0053] Traditional golf balls were designed to have the dimples trip theboundary layer on the surface of a golf ball in flight to create aturbulent flow for greater lift and reduced drag. The golf ball 20 ofthe present invention has the lattice structure 42 to trip the boundarylayer of air about the surface of the golf ball 20 in flight.

[0054] As shown in FIG. 4A, a 1.68 inches outersphere, as shown bydashed line 45, encompasses the lattice members 40 and the innersphere21. The volume of the lattice structure 42 as measured from the bottomof each lattice member 40 to the apex 50 is a minimal amount of thevolume between the 1.68 inches outersphere and the innersphere 21. Inthe preferred embodiment, the apex 50 lies on the 1.68 inchesoutersphere. Thus, over 90 percent, and closer to 95 percent, of theentire volume of the golf ball 20 lies below the 1.68 inchesoutersphere.

[0055] As shown in FIGS. 5 and 6, the distance h and h″ of the latticemembers 40 from the bottom of each lattice member 40 to an apex 50 willvary in order to have the golf ball 20 meet or exceed the 1.68 inchesrequirement. For example, if the diameter of the innersphere 21 is 1.666inches, then the distance h of the lattice members 40 in FIG. 5 is 0.007inch since the lattice member 40 on one hemisphere 26 is combined with acorresponding lattice member 40 on the second hemisphere 28 to reach the1.68 inches requirement. In a preferred embodiment, if lattice members40 having a greater distance h″ are desired, such as in FIG. 6, then theinnersphere 21 has a lesser diameter. Thus, the diameter of theinnersphere 21 in FIG. 6 is 1.662 while the distance h″ of the latticemembers 40 are 0.009 inch thereby resulting in an outersphere with adiameter of 1.68 inches. As shown in FIG. 6A, the width of each of theapices 50 is minimal since the apex lies along an arc of a latticemember 40. In theory, the width of each apex 50 should approach thewidth of a line. In practice, the width of each apex 50 of each latticemember 40 is determined by the precision of the mold utilized to producethe golf ball 20. The precision of the mold is itself determined by themaster used to form the mold. In the practice, the width of each lineranges from 0.0001 inch to 0.001 inch.

[0056] Although the cross-section of the lattice members 40 shown inFIGS. 5 and 6 are circular, a preferred cross-section of each of theplurality of lattice members 40 is shown in FIGS. 7 and 8. In such apreferred cross-section, the lattice member 40 has a contour 52 that hasa first concave section 54, a convex section 56 and a second concavesection 58. The radius R₂ of the convex portion 56 of each of thelattice members 40 is preferably in the range of 0.0275 inch to 0.0350inch. The radius R₁ of the first and second concave portions 54 and 58is preferably in the range of 0.150 inch to 0.200 inch, and mostpreferably 0.175 inch. R_(IS) is the radius of the innersphere, which ispreferably 0.831 inch. R_(OS) is the radius of the outersphere, which ispreferably 1.68 inches.

[0057] A preferred embodiment of the present invention is illustrated inFIGS. 9, 9A, 9B and 9C. In this embodiment, the golf ball 20 has aparting line 100 that corresponds to the shape of polygon defined by theplurality of lattice members 40 about the equator 24. Thus, if thepolygons have a hexagonal shape, the parting line 100 will alternatealong the lower half of one hexagon and the upper half of an adjacenthexagon. In the embodiment of FIGS. 9, 9A, 9B and 9C, there are 332polygons, with 12 of those polygons being pentagons and the rest beinghexagons.

[0058] As shown in FIG. 9, each hemisphere 26 and 28 has two rows ofhexagons 70, 72, 74 and 76, adjacent the parting line 100. The pole 30of the first hemisphere 26 is encompassed by a pentagon 44 b, as shownin FIG. 9B. The pentagon 44 b at the pole 30 is encompassed by everincreasing spherical pentagonal groups of hexagons 80, 82, 84, 86, and88. A pentagonal group 90 has pentagons 44 b at each respective base,with hexagons 44 a therebetween. The pentagonal groups 80, 82, 84, 86,88 and 90 transform into the four adjacent rows 70, 72, 74 and 76. Thepreferred embodiment only has hexagons 44 a and pentagons 44 b.

[0059]FIG. 10 is an enlarged view of the surface of the golf ball 20 ofthe present invention to demonstrate the minimal volume of the golf ball20 from a predetermined distance from the greatest extent of the golfball 20, the outersphere. More specifically, the greatest extent of oneembodiment of the golf ball 20 are the apices 50 of the lattice members40 which lie on a spherical plane (shown as dashed line 45) which has a1.682 inches diameter, the outersphere. Those skilled in the art shouldrecognize that other embodiments could have the apices 50 lie on aspherical plane at 1.70 inches, 1.72 inches, 1.64 inches, 1.60 inches,or any other variation in the diameter of the greatest extent of thegolf ball 20. Having defined the greatest extent of the golf ball 20,the present invention will have a minimal volume from this greatestextent toward the innersphere 22. For example, dashed line 130represents a spherical plane that intersects each of the lattice members40 at a distance of 0.002 inch (at a radius of 0.839 inch from thecenter) from the greatest extent of the golf ball 20. The volume of thegolf ball 20 of the present invention between the greatest extentspherical plane 45 and the spherical plane 130 is only 0.0008134 cubicinch. In other words, the outermost 0.002 inch (between a radius of0.841 and 0.839 inch) of the golf ball 20 has a volume 0.0008134 cubicinch.

[0060]FIG. 11 illustrates the surface of a golf ball 140 of the priorart which has traditional dimples 142 encompassed by a land area 144.The land area 144 represents the greatest extent of the golf ball 140 ofthe prior art. For comparison to the golf ball 20 of the presentinvention, the volume of the golf ball 140 of the prior art between thegreatest extent 144 and a spherical plane 130″ is 0.00213 cubic inch.Spherical planes 132, 134 and 136, at 0.004 inch, 0.006 inch and 0.008inch respectively, have volumes of 0.0023074 cubic inch, 0.0042164 cubicinch and 0.0065404 cubic inch, respectively on the golf ball 20 of thepresent invention. Spherical planes 132″, 134″ and 136″, at 0.004 inch,0.006 inch and 0.008 inch respectively, will have volumes of 0.00498cubic inch, 0.00841 cubic inch and 0.01238 cubic inch on the golf ball140 of the prior art 140.

[0061] Thus, as further shown in FIG. 12 and Table One below, the golfball 20 of the present invention preferably has a minimal volume at apredetermined distance from the greatest extent of the golf ball 20.This minimal volume is a minimal amount necessary to trip the boundarylayer air at low speed while providing a low drag level at high speeds.The first column of Table One is the distance from the outermost pointof the golf ball 20, which is the apex 50 of each of the lattice members40. The second column is the individual volume of each of the 830lattice members 40 at this distance inward from the outermost point. Thethird column is the total volume of the spherical planes at eachdistance inward from the outermost point. Table Two contains similarinformation for the golf ball 140 of the prior art.

[0062] [t1] TABLE ONE Tube H Tube Vol Total Volume 0.001 0.000000350.0002905 0.002 0.00000098 0.0008134 0.003 0.00000181 0.0015023 0.0040.00000278 0.0023074 0.005 0.00000387 0.0032121 0.006 0.000005080.0042164 0.007 0.00000641 0.0053203 0.008 0.00000788 0.0065404 0.0090.00001123 0.0093209

[0063] [t2] TABLE TWO Shell Delta Dia. 1/10 Remaining Vol TotalRemaining Vol 0.001 0.000091 0.00091 0.002 0.000213 0.00213 0.0030.000347 0.00347 0.004 0.000498 0.00498 0.005 0.000663 0.00663 0.0060.000841 0.00841 0.007 0.001033 0.01033 0.008 0.001238 0.01238 0.0090.001458 0.01458

[0064] The aerodynamic pattern of the golf ball 20 is combined with atwo-piece golf ball construction that has a relatively medium hardnesscover 14 encompassing the core 12 with a relatively medium corecompression. The construction of the golf ball 20 allows for a golf ball20 that has a softer hardness while providing greater velocity thanother competitive golf balls.

[0065] The coefficient of restitution (COR) is a measure of theresilience of a golf ball. The COR is a measure of the ratio of therelative velocity of the golf ball after direct impact with a hardsurface to the relative velocity before impact with the hard surface.The COR may vary from 0 to 1, with 1 equivalent to a completely elasticcollision and 0 equivalent to a completely inelastic collision. A golfball having a COR value closer to 1 will generally correspond to a golfball having a higher initial velocity and a greater overall distance.The force of a club during a swing is transferred to a golf ball. If thegolf ball has a high COR (more elastic), then the initial velocity ofthe golf ball will be greater than if the golf ball had a low COR. Ingeneral, a higher compression core will result in a higher COR value.The COR of the core 12 of the golf ball 20 of the present invention ispreferably 75 to 80 points at 143 feet per second (fps), most preferablyranging from 76 to 79 points at 143 fps, and is most preferably 78.34points at 143 fps.

[0066] In the present invention, the core components are mixed andcompression molded in a conventional manner known to those skilled inthe art. In a preferred form, the finished core 12 has a diameter ofabout 1.50 inch to about 1.62 inch for a golf ball 20 having an outerdiameter of 1.68 inches, and is most preferably 1.535 to 1.545, with1.54 the preferable diameter of the core 12. The core weight ispreferably maintained in the range of about 32 to about 40 g, with 34grams to 38 grams a more preferably range and 36 grams the mostpreferable weight of the core 12. The core PGA compression is preferablymaintained in the range of about 47 to 62, and most preferably rangeabout 53 to 57 with 55 the most preferable core compression.

[0067] As used herein, the term PGA compression is defined asfollows:PGA compression value=180 Riehle compression valueThe Riehlecompression value is the amount of deformation of a golf ball in inchesunder a static load of 200 pounds, multiplied by 1000. Accordingly, fora deformation of 0.095 inches under a load of 200 pounds, the Riehlecompression value is 95 and the PGA compression value is 85.

[0068] The core 12 of the golf ball 20 is generally composed of a blendof a base rubber, a cross-linking agent, a free radical initiator,tungsten and one or more fillers or processing aids. A preferred baserubber is a polybutadiene having a cis-1,4 content above 90%, and morepreferably 98% or above.

[0069] The use of cross-linking agents in a golf ball core is wellknown, and metal acrylate salts are examples of such cross-linkingagents. For example, metal salt diacrylates, dimethacrylates, ormono(meth)acrylates are preferred for use in the golf ball cores of thepresent invention, and zinc diacrylate is a particularly preferredcross-linking agent. A commercially available suitable zinc diacrylateis SR-416 available from Sartomer Co., Inc., Exton, Pa. Other metal saltdi- or mono-(meth)acrylates suitable for use in the present inventioninclude those in which the metal is calcium or magnesium. In themanufacturing process it may be beneficial to pre-mix some cross-linkingagent(s), such as, e.g., zinc diacrylate, with the polybutadiene in amaster batch prior to blending with other core components. A preferredmixing process is disclosed in co-pending U.S. patent application Ser.No. 09/690,373 filed on Oct. 16, 2000, entitled A Process ForManufacturing A Core For A Golf Ball, which pertinent parts are herebyincorporated by reference.

[0070] Free radical initiators are used to promote cross-linking of thebase rubber and the cross-linking agent. Suitable free radicalinitiators for use in the golf ball core 12 of the present inventioninclude peroxides such as dicumyl peroxide, bis-(t-butyl peroxy)diisopropyl benzene, t-butyl perbenzoate, di-t-butyl peroxide,2,5-dimethyl-2,5-di-5-butylperoxy-hexane, 1,1-di(t-butylperoxy)3,3,5-trimethyl cyclohexane, and the like, all of which are readilycommercially available.

[0071] Zinc oxide is also preferably included in the core formulation.Zinc oxide may primarily be used as a weight adjusting filler, and isalso believed to participate in the cross-linking of the othercomponents of the core (e.g. as a coagent). Additional processing aidssuch as dispersants and activators may optionally be included. Inparticular, zinc stearate may be added as a processing aid (e.g. as anactivator).

[0072] Tungsten is added to the core mixture to provide weight to thecore 12, and hence the golf ball 10, while occupying volume minimalvolume. Tungsten has a density of 19.3 grams per centimeter cubed whichis much greater than the density of the polybutadiene. Thus, minimaltungsten allows for the necessary weight while allowing for morepolybutadiene to be used in the core 12 to provide greater velocity. Anumber of other specific gravity adjusting fillers, in addition to thetungsten, may be included to obtain a preferred total weight of the core12. Examples of such fillers include clay and barium sulfate. All suchprocessing aids and fillers are readily commercially available. Thepresent inventors have found a particularly useful tungsten filler isWP102 Tungsten (having a 3 micron particle size) available from AtlanticEquipment Engineers, Bergenfield, N.J.

[0073] Table Three below provides the ranges of materials included inthe preferred core formulations of the present invention.

[0074] [t3] TABLE THREE Component Preferred Range Most Preferred RangePolybutadiene 100 parts 100 parts Zinc diacrylate 20-35 phr 25-30 phrZinc oxide  0-50 phr  5-15 phr Zinc stearate  0-15 phr 1-7 phr Peroxide0.2-2.5 phr 0.5-1.5 phr Filler As desired As desired Tungsten  6-10 phr6 phr

[0075] The preferred specific gravity for the core 12 is 1.165 to 1.185,and most preferably 1.174.

[0076] The cover 14 preferably is composed of a thermoplastic material(e.g. thermoplastic or thermoplastic elastomer) or a blend ofthermoplastic material (e.g. metal containing, non-metal containing orboth). Most preferably the cover 14 is composed of a blend ofthermoplastic materials that contain organic chain molecules and metalions. The metal ion may be, for example, sodium, zinc, magnesium,lithium, potassium, cesium, or any polar metal ion that serves as areversible cross-linking site and results in high levels of resilienceand impact resistance. Suitable commercially available thermoplasticsare ionomers based on ethylene copolymers and containing carboxylic acidgroups with metal ions such as described above. The acid levels in suchsuitable ionomers may be neutralized to control resiliency, impactresistance and other like properties.

[0077] In addition, other fillers with ionomer carriers may be used tomodify (e.g. preferably increase) the specific gravity of thethermoplastic blend to control the moment of inertia and other likeproperties. Exemplary commercially available thermoplastic materialssuitable for use in a cover 14 of a golf ball 20 of the presentinvention include, for example, the following materials and/or blends ofthe following materials: HYTREL® and/or HYLENE® products from DuPont,Wilmington, Del., PEBAX® products from Elf Atochem, Philadelphia, Pa.,SURLYN® products from DuPont, and/or ESCOR® or IOTEK ® products fromExxon Chemical, Houston, Tex.

[0078] The Shore D hardness of the cover 14 should be about 62 or less.It is preferred that the cover 14 have a hardness of between about 54-64Shore D, more preferably from 58 to 63, and most preferably 62. Onereason for preferring a cover 14 with a Shore D hardness of 62 to 58 isto improve the feel of the resultant golf ball. The Shore D Hardness isdetermined according to ASTM D2240. However, the comparative testing inFIGS. 13-14 tested the Shore D hardness on the land surface of an actualgolf ball by using a Shore D durometer tester while the golf ball wasfixed within a holder.

[0079] It is preferred that the cover 14 is composed of a blend ofSURLYN® ionomer resins. SURLYN® 9150 and 6320 are an ionomer resincomposed of a zinc neutralized ethylene/methacrylic acid and an ionomerresin composed of a terpolymer of ethylene, methacrylic acid and n-butylacrylate partially neutralized with magnesium, and both are availablefrom DuPont, Polymer Products, Wilmington, Del.

[0080] Preferably the blend of ionomers that form the cover 14 iscomposed of 60 to 70 weight percent composed of a zinc neutralizedethylene/methacrylic acid ionomer resin (SURLYN 9150), and 40 to 30weight percent of an ionomer resin composed of a terpolymer of ethylene,methacrylic acid and n-butyl acrylate partially neutralized withmagnesium (SURLYN 6320). A most preferred embodiment is composed of 65weight percent composed of a zinc neutralized ethylene/methacrylic acidionomer resin (SURLYN 9150), and 35 weight percent of an ionomer resincomposed of a terpolymer of ethylene, methacrylic acid and n-butylacrylate partially neutralized with magnesium (SURLYN 6320).

[0081] Preferably, the ionomer resins are mixed and heated, theninjection molded in a flowable form over the core 12 in a conventionalmanner that is well-known to those skilled in the pertinent art to formthe cover 14. The mold has an inverse aerodynamic pattern to form theaerodynamic pattern on the cover 14. Alternatively, the cover 14 may bemanufactured using half shells that are compression molded over the core12, which is also well-known in the pertinent art.

[0082] An alternative embodiment of the cover 14 may include apredetermined amount of a baryte mixture. The baryte mixture is includedas 8 or 9 parts per hundred parts of the ionomer resins. One preferredbaryte mixture is composed of 80% barytes and 20% of an ionomer, and isavailable from Americhem, Inc., Cuyahoga Falls, Ohio, under the tradedesignation 38534X1.

[0083] The cover 14 preferably has a thickness of 0.60 inch to 0.90inch, most preferably ranging from 0.65 inch to 0.80 inch, and mostpreferably 0.70 inch. Preferably, the apex of the lattice ember 42 is0.070 inch from the surface of the core 12 and the innersphere surface21 is 0.0615 inch from the surface of the core 12. The cover 14preferably has a flexural modulus (using ASTM-790) of 35,000 pounds persquare inch (psi) to 60,000 psi, most preferably 50,000 psi. The golfball 20 is preferably finished by applying a base coat and/or top coatto the surface of the cover 14 for whiteness and protection. Also, alogo marking may be applied to the base coat or top coat. The finishedgolf ball 20 has a weight of 45 to 46 grams, preferably 45.65 grams. Thegolf ball 20 has a PGA compression of 65 to 90 points, preferably 75 to85 points, and most preferably 80 points. The golf ball 10 has a COR of74 to 84 points, preferably 76 to 82 points, and most preferably 79points at 143 fps.

[0084] Table Four is a comparison of the golf ball 20 of the presentinvention and other competitive golf balls on the market.

[0085] [t4] TABLE FOUR Medium Med. Speed Speed Cover 5-iron Driver BallCore Ball Ball Shore D Ball Ball Velocity Velocity Ball Compression CORRebound Hardness Compression (mph) (mph) Golf ball 20 55 0.7834 77.9861.8 78 115.35 133.67 Precept MC 83 0.7687 76.68333 54.33333 93.625113.626833 131.6555 Spin Precept MC 64.66667 0.787 78.01667 64.6666791.25 114.4907 132.836167 Distance Precept MC 40.83334 0.7872 77.8560.66667 73.70833 114.543083 132.441917 Lady Titleist DT 74.75 0.795379.88333 68.66667 91.08333 114.7595 133.509667 Distance Titleist HP54.91638 0.7712 78.41667 69 82.04167 114.115833 131.884417 DistanceTitleist HP 82.58334 0.7566 75.85 64 98 112.996455 130.472167 EclipseStaff Titanium 28.33333 0.8026 80.45 70.33333 88.91666 115.753091133.690917 Straight Distance Staff Smart-Core 33.41666 0.8042 80.3166770 90.59091 115.624091 133.69725 Straight Distance Nike Distance71.91667 0.7868 77.73333 64.66667 100.0833 114.629333 132.866167 ControlTaylor Made 84.25 0.7697 79.96667 65.33333 105.1667 113.893545131.928833 Intergel Pro Distance Slazenger Raw 81.5 0.8036 79.93333 70104.0833 115.33075 143.276917 Distance 3 Strata 47.25 0.7873 77.93333 6599.75 114.565455 132.755333 Distance 90

[0086] The ball compression for each golf ball in Table Four wasmeasured using the PGA compression test described above for several golfballs and taking the mean value. The core compression for each golf ballin Table Four was measured by removing the cover and subjecting the coreof each golf ball to a PGA compression test as described above forseveral golf balls and taking the mean value. The Ball COR for each golfball in Table Four was measured by firing each golf ball at 143 fps at asolid wall as described above for several golf balls and taking the meanvalue. The cover hardness for each golf ball in Table Four was measuredon the land surface of the golf ball using a Shore D durometer asdescribed above for several golf balls and taking the mean value. Theball rebound for each golf ball in Table Four was measured by droppingeach golf ball at a predetermined height at a solid floor as measuringthe rebound for several golf balls and taking the mean value. The mediumspeed 5-iron ball velocity for each golf ball in Table Two wasdetermined by hitting each golf ball with a Callaway Golf® STEELHEAD™X-14® five iron at a speed of approximately 79 miles per hour (MPH) forseveral golf balls and taking the mean value. The medium speed driverball velocity for each golf ball in Table Two was determined by hittingeach golf ball with a Callaway Golf® BIG BERTHA® HAWK EYE® VFT™ tendegree driver at a speed of approximately 90 miles per hour (MPH) forseveral golf balls and taking the mean value.

[0087] As shown in FIG. 13, the golf ball 20 of the present invention isthe only golf ball that has a Shore D hardness less than 64 and a ballvelocity off a driver at a medium speed that is greater than 132.7 mph.More specifically, the golf ball 20 of the present invention is the onlygolf ball that has a Shore D hardness less than 63 and a ball velocityoff a driver at a medium speed that is greater than 133.0 mph. Mostspecifically, the golf ball 20 of the present invention is the only golfball that has a Shore D hardness less than 62 and a ball velocity off adriver at a medium speed that is greater than 133.5 mph.

[0088] As shown in FIG. 14, the golf ball 20 of the present invention isthe only golf ball that has a Shore D hardness less than 68 and a ballvelocity off a five-iron at a medium speed that is greater than 115.0mph. More specifically, the golf ball 20 of the present invention is theonly golf ball that has a Shore D hardness less than 64 and a ballvelocity off a five-iron at a medium speed that is greater than 115.0mph. Most specifically, the golf ball 20 of the present invention is theonly golf ball that has a Shore D hardness less than 62 and a ballvelocity off a five iron at a medium speed that is greater than 115.5mph.

[0089] From the foregoing it is believed that those skilled in thepertinent art will recognize the meritorious advancement of thisinvention and will readily understand that while the present inventionhas been described in association with a preferred embodiment thereof,and other embodiments illustrated in the accompanying drawings, numerouschanges, modifications and substitutions of equivalents may be madetherein without departing from the spirit and scope of this inventionwhich is intended to be unlimited by the foregoing except as may appearin the following appended claims. Therefore, the embodiments of theinvention in which an exclusive property or privilege is claimed aredefined in the following appended claims.

We claim as our invention:
 1. A golf ball comprising: a core having adiameter of 1.50 inches to 1.56 inches, the core comprisingpolybutadiene, zinc oxide in an amount of 7 to 15 parts per hundredparts of polybutadiene, zinc diacryalate in an amount of 30 to 50 partsper hundred parts of polybutadiene; an initiator in an amount of 0.1 to1.0 parts per hundred parts of polybutadiene, and tungsten in an amountof 5 to 10 parts per hundred parts of polybutadiene, the core having aPGA compression of 45 to 65 points; and a cover having a thickness of0.060 inch to 0.090 inch, the cover comprising an ionomer blend formedfrom a high acid ionomer neutralized with zinc and a terpolymerneutralized with magnesium, the cover having a flexural modulus rangingfrom 35,000 psi to 60,000 psi, a Shore D hardness ranging from 60 to 65;wherein the golf ball has a PGA compression ranging from 75 to 85points, and the golf ball has a lattice structure aerodynamic pattern.2. A golf ball comprising: a core having a diameter of 1.50 inches to1.56 inches, the core having a PGA compression of 45 to 65 points; and acover having a thickness of 0.060 inch to 0.090 inch, the cover having aShore D hardness less than 64 as measured on the land surface of thegolf ball; wherein the golf ball has a ball velocity off a driver at amedium speed that is greater than 132.7 mph, and wherein the golf ballhas an innersphere having a diameter in the range of 1.60 to 1.78inches, a plurality of smooth portions on the surface of the innersphereand a plurality of lattice members.
 3. A golf ball comprising: a corehaving a diameter of 1.50 inches to 1.56 inches, the core having a PGAcompression of 45 to 65 points; and a cover having a thickness of 0.060inch to 0.090 inch, the cover having a Shore D hardness less than 64 asmeasured on the land surface of the golf ball; wherein the golf ball hasa ball velocity off a five iron at a medium speed that is greater than115.0 mph, and wherein the golf ball has an innersphere having adiameter in the range of 1.60 to 1.78 inches, a plurality of smoothportions on the surface of the innersphere and a plurality of latticemembers.
 4. A golf ball comprising: a core having a diameter of 1.50inches to 1.56 inches, the core having a PGA compression of 45 to 65points; and a cover having a thickness of 0.060 inch to 0.090 inch, thecover having a Shore D hardness less than 64 as measured on the landsurface of the golf ball; wherein the golf ball has a COR that isgreater than 0.783 points at 143 fps, and wherein the golf ball has aninnersphere having a diameter in the range of 1.60 to 1.78 inches, aplurality of smooth portions on the surface of the innersphere and aplurality of lattice members.
 5. A golf ball comprising: a core having adiameter of 1.50 inches to 1.56 inches, the core having a PGAcompression of 45 to 65 points; a cover having a thickness of 0.060 inchto 0.090 inch, the cover having a Shore D hardness less than 64 asmeasured on the land surface of the golf ball; an innersphere having asurface; a plurality of smooth portions on the surface of theinnersphere; and a plurality of lattice members encompassing theplurality of smooth portions, each of the lattice members having across-sectional curvature comprising a first concave portion, a secondconcave portion and a convex portion disposed between the first concaveportion and the second concave portion, the convex portion having anapex tangent to the curvature of the convex portion, each of theplurality of lattice members connected to at least one other latticemember to form a predetermined pattern of polygons about the pluralityof smooth portions, each of the lattice members having an apex at adistance of from 0.005 inch to 0.010 inch from the bottom of the latticemember thereby defining an outersphere.
 6. A golf ball comprising: acore having a diameter of 1.50 inches to 1.56 inches, the core having aPGA compression of 45 to 65 points; a cover having a thickness of 0.060inch to 0.090 inch, the cover having a Shore D hardness less than 64 asmeasured on the land surface of the golf ball; an innersphere having asurface; a plurality of smooth portions on the surface of theinnersphere; and a plurality of lattice members disposed on theinnersphere surface, each of the lattice members having across-sectional curvature with an arc and an apex at the highest pointof the arc of each of the lattice members that is tangent to thecurvature of the arc, each of the plurality of lattice members connectedto at least one other lattice member to form a plurality ofinterconnected polygons about each of the plurality of smooth portions;wherein the lattice members cover between 20% and 80% of the surface ofthe golf ball, and the plurality of smooth portions and the plurality oflattice members cover the entirety of the surface of the golf ball.
 7. Agolf ball comprising: a core having a diameter of 1.50 inches to 1.56inches, the core having a PGA compression of 45 to 65 points; a coverhaving a thickness of 0.060 inch to 0.090 inch, the cover having a ShoreD hardness less than 64 as measured on the land surface of the golfball; a plurality of lattice members wherein an apex of at least one ofthe plurality of lattice members defines the greatest extent of the golfball, wherein the volume of the outermost 0.002 inch of the golf ball isless than 0.00213 cubic inch.
 8. The golf ball according to claim 7wherein the volume of the outermost 0.004 inch of the golf ball is lessthan 0.00498 cubic inch.